The length of the commutation cycle and/or the duty cycle of a switched-mode power converter (e.g. a boost-converter, a buck converter or a buck-boost converter) may be controlled using hysteretic control. In order to perform a hysteretic control, the current within the switched-mode power converter must be measured to realize the control feedback to a hysteretic comparator within the driver circuit. The sensing of the current within the switched-mode power converter may be performed using external current sensing components which are external to the driver circuit.
The use of an external current sensing component is disadvantageous because it increases the area consumption on the board of an integrated circuit (IC) comprising the switched-mode power converter. Furthermore, the external current sensing component leads to additional cost, notably when requiring high accuracy measurements. The cost can be lowered by choosing e.g. a chip resistance, but the system typically suffers due to the lower tolerance of cheaper current sensing components. This leads to the fact that the inaccuracy cannot be compensated for on the chip. In addition, the use of an external current sensing component increases the pin count, because an additional pin is required for the current measurement.
The present document addresses the above mentioned shortcomings of switched-mode power converters which are submitted to hysteretic control. In particular, the present document describes a driver circuit for the hysteretic control of a switched-mode power converter, wherein the driver circuit does not make use of external current sensing means. As a result, the driver circuit has a reduced pin count and an IC comprising the switched-mode power converter can be implemented in a cost efficient manner.